https://bugs.winehq.org/show_bug.cgi?id=26803
--- Comment #14 from Bruno Jesus 00cpxxx@gmail.com --- (In reply to Lauri Kenttä from comment #12)
I had a closer look at this.
FILEDLG95_FILENAME_FillFromSelection is somewhat poorly implemented, it loops the files twice, calls GlobalLock many times etc. Still, fixing this function improves speed only by 30% for 250 files (depends on the number of files).
That sounds like a pretty good start, please send these improving patches.